Lubricating composition and method of making same



Patented on. 11, 1939 UNITED s'mras PATENT OFFICE LUBRICATING COMPOSITION AND METHOD OF MAKING SAME -Paul La Frone Magill, Ransomville, N. Y., as-

signor to E. I. du Pont de Neniours & Company, Wilmington, Del.,. a corporation of Delaware No Drawing. Original application July 29,. 1937,

Serial No. 156,424.

Divided and this application April 22, 1938, Serial No. 203,702

4 Claims. ('01. 87-9) extreme pressure lubricants and the like.. Other objects will be apparent from the ensuing description of my invention.

The above objects may be accomplished in ac cordance with my invention by heating a dihydro polycyclic aromatic hydrocarbon or a homologue thereof with sulfur to form a sulfur reaction product of said dihydro hydrocarbon and, when it is desired to employ the product asa lubricant assistant, incorporating the product into a lubricating oil. i

I have discovered that sulfur may be reacted with dihydro polycyclic aromatic hydrocarbons or their homologues, e. g., the alkyl derivatives of such dihydro hydrocarbons, to give products which appear to be definite compounds, although the nature of the reaction involved and the exact identity of the products formed are not entirely understood. In the specification and in the appended claims, I use the term dihydro polycyclic aromatic hydrocarbons" to include'those polycyclic hydrocarbons and their homologues whose molecular structure includes a benzene nucleus in addition to a partially hydrogenated carbon ring, e. g., a partially hydrogenated benzene ring, said partially hydrogenated ring containing at least one double bond linkage. Dihydl'onaphthalene, dihydrodiphenyl, dihydroacenaphthene and dihydrophenanthrene are mentioned as illustrative of the dihydro polycyclic aromatic hydrocarbons that may be used. Thus, when dihydronaphthalene is heated with sulfur an exothermic reaction takes place to produce a straw colored, clear oil, the molecular weight of which in general increases as the sulfur content increases. The reaction occurs substantially without hydrogen sulfide evolution, which distinguishes it from the reactionof sulfur with aliphatic compounds. The maximum amount of sulfur that may be reacted with dihydronaphthalene s lim ted in t a w en the re t p od i is employed.

uct contains more than 25-26% of sulfur, un-

reacted sulfur separates from" the mixture on cooling to room temperature. In general, the molecular weight of theproduct is approximately 260 when the maximum amount of sulfur is contained therein.

The dihydronaphthalefie which is most suitable for preparing the "present sulfur product is 1,4-dihydronaphthalene. The 1,2-dihydronaphthalene may also be employed with good results; however, this hydrocarbon is not as readily obtainable as is the 1,4-dihydro compound. The dihydronaphthalene which I prefer to employ may be readily prepared by the 'method which is described in the Scott and Walker United States Patent 2,055,708 which issued September 29, 1936. The product obtained by the method of the patent consists mainly of 1,4-dihydronaphthalene but also includes some of the 1,2-dihydro compound as well as some unreacted naphthalene. The presence'of naphthalene as an impurity is not objectionable. I f

The dihydro derivatives of other polycyclic aromatic hydrocarbons or their homologues, in general, may also be prepared by the method de' scribed in the above patent for the preparation of dihydronaphthalene. However, my invention is not limited to the use of compounds prepared by the-method of this patent, since any dihydro polycyclic aromatic hydrocarbon or its homologues, regardless of its method of preparation,

may-be employed with excellent results. f The preparation of thesulfurlzed dihydro hydrocarbons of my invention is illustrated by the following example wherein dihydronaphthalene I Example w A mixture of sulfur and dihydronaphthalene (principally the 1,4.-dihydro compound containing about 20% of naphthalene as an impurity) in the proportion of one mole of dihydronaphthalene to one atom of sulfur was heated in a nitrogen atmosphere during constant agitation.

As the temperature reached approximately" 0., an exothermic reaction took place. The heating was continued for 1 /2 hours at C. and thereafter the mixture was cooled to room temperature when the naphthalene impurity precipitated'andwas filtered out. The product ob-' tained was a straw colored, clear oil containing 24% of sulfur.

In a' similar run, twice the amount of sulfur was, employed and the unreacted sulfur was separated from the mixture by dissolving the reaction mixture in petroleum ether. The product cific proportions of sulfur and the dihydro hydro-- carbon in preparing the sulfurized product. However, there is generally no advantage in employing sulfur in quantities greater than that requiredt to give a reaction product containing more than -26% by weight of sulfur since sulfur in excess of this amount precipitates from the product. The use of one atomic proportion of sulfur to 0.7 to 2.5 molecular proportions ofthe dihydro polycyclic aromatic hydrocarbon is generally preferred since under such circumstances substantially all of the sulfur is reacted. Thus, by reacting one atom of sulfur with 0.7 moles of dihydronaphthalene, a product containing 25-26% sulfur is obtained. If the proportion of dihydronaphthalenes is incr ased to 2.5 moles per one atom of sulfur, the resulting product will contain about 8.9% of sulfur.

If desired, the reaction product may be isolated by distillation under reduced pressures, e. g., 4 mm. Also, sulfur which is unreacted but merely dissolved in the reaction product may be removed therefrom by treatment with a solvent, e. g., petroleum ether, in which sulfur is insoluble, so as to separate the unreacted sulfur, the desired product being separated by distillation from its.

solution in the solvent. However, for most purposes for which the product may be used, the

presence of impurities such as unreacted sulfur is not objectionable and purification of the reaction mixture by the above or other methods is not necessary.

The rate of reaction hetweensulfur and the dihydro hydrocarbon usually is not sufilciently rapid at temperatures substantially below 140 C. for practical purposes. On the other hand, control of the reaction, which is exothermic, at temperatures in excess of about 170 C. is diffi cult. It is therefore preferred to effect the reaction at a temperature of about 140-170" C. However, by employing reaction mixtures which are diluted by inert solvents, it may be possible to carry out the reaction in accordance withmy invention at temperatures in excess of 170 C. Control of the rated reaction may also be facilitated byheating the dihydro polycyclic aromatic hydrocarbon to the desired reaction temperature, .e. g., by

7 means of an oil-bath, and then adding the sulfur thereto in small increments. It will be understood that the above stated optimum reaction temperatures are approximate and will vary more or less for difierent hydrocarbons employed. In

most cases, however, I prefer to employ a reaction temperature of 140 to 170 C.

One important characteristic of my sulfurized hydrocarbons is that they are homogeneous mono-phase liquids, i. e., they c tain no suspended solid or other materials. Thus the dihydronaphthalene-sulfur reaction product is a straw-colored clear oil.

My sulfurized hydrocarbons are soluble in various organic solventsand particularly the hydrocarbon solvents and their chlorinated products.

Thus, they are soluble in petroleum and. vegeare generally desired for cutting oils.

table oils, the ordinary chlorinated hydrocarbon solvents, benzene, toluene, waxes and greases and the like. Because theproducts are clear liquids and are readily soluble in numerous solvents, they are of potential value for many purposes where sulfur or sulfurized products are required. In particular, I have found that these products are well suited for use as lubricant assistants in lubricating compositions such as-cutting oils, high pressure lubricants, greases and the like.

The products are particularly suitable for use in cutting oils since they not only appreciably increase and improve the lubricating properties of the compositions but also are easily miscible with the oil base to give clear compositions which By means of my invention, relatively large amounts of sulfur may be added to a cutting oil without darkening the same. This is an important advantage, since light colored, transparent oils are essential for cutting oil applications. The amount of the sulfurized product, e. g., the reaction product of dihydronaphthalene and sulfur, that need be added to the oil will vary with the use for which the oil is intended. In general, I find it suitable to add the sulfurized product in such quantities so as to give a sulfur content in the cutting oil under such circumstances the load carrying capacity of the gear oil is markedly increased. My invention is not limited to the addition of the above sulfurized products to oils of any particular viscosity, nor to hydrocarbon oils, since such compositions may be added to high or low viscosity mineral oils, including greases, as well as to oils of vegetable origin with excellent results. Because my sulfurized dihydronaphthalene is a liquid at ordinary temperature, it may be easily incorporated in any desired amount into cutting oils or extreme pressure lubricating compositions and the like. If the composition into which it is to be incorporated is relatively viscous at ordinary temperature, it is best to heat the composition so as to facilitate thorough dispersion of the sulfur product therein.

It is to be understood that that modification of my inv ntion which relates to the use of the present furized products as lubricant assistants is not limited to the particular concentrations mentioned above as illustrative since the amount of sulfur desired in lubricating compositions may vary within wide limits depending upon the use for which such compositions are desired. It will be apparent to those skilled in the preparation of such compositions that the present sulfurized products may be employed to give any embodiments since they are merely illustrative and not restrictive of my invention. My invention is to be limited only by the scope of the appended claims.

In the appended claims, the term lubricating compositions is used to designate oleaginous compositions in general which have lubricating properties, regardless of whether the lubricating base is of mineral or vegetableorigin. It also designates compositions of high or low viscosity, including, for example, cutting oils, light lubricating oils, extreme pressure lubricating compositions, greases and the like. The term lubricating oil is used to designate any solid or liquid substance of either mineral or vegetable origin 1. A lubricating composition comprising a lubricating oil and a homogeneous, mono-phase, liquid reaction product of a dihydro polycyclic aromatic hydrocarbon and sulfur.

2. A lubricating composition comprising a lubricating oil and a homogeneous, mono-phase, liquid reaction product of a dihydro polycyclic aromatic hydrocarbon and sulfur, said reaction product containing about 8.9 to 26% of sulfur.

3. A lubricating composition comprising a lubricating oil and a homogeneous, mono-phase,

liquid reaction product of dihydronaphthalene and sulfur.

4. A lubricating composition comprising a lubricating oil and a homogeneous, mono-phase, liquid reaction product of dihydronaphthalene and sulfur, said reaction product containing about 8.9 to 26% of sulfur.

PAUL LA FRONE MAGILL. 

